Field of Invention
The present invention relates to a tool, and more particular to a rotary cutting tool with a positioning arrangement, which has the advantages of strong radial impact resistance, high positioning accuracy, high safety concern and long service life.
Description of Related Arts
As shown in FIGS. 1 and 2, a conventional rotary cutting tool comprises a rotary cutting body 1, a clamp 2, a cutting insert 3, a clamp fastener 4, and an insert fastener 5. The rotary cutting body 1 has at least an insert pocket 11, wherein the cutting insert 3 is affixed at the clamp 2 by the insert fastener 5, such that the cutting insert 3 and the clamp 2 together are affixed at the insert pocket 11. In particular, the clamp fastener 4 is extended through a hole on the rotary cutting body 1 to couple at the clamp 2 via a threaded engagement structure, such that the threaded portion of the clamp fastener 4 is engaged with the threaded portion of the clamp 2 (which is made of steel) without directly engaging with the threaded portion of the rotary cutting body 1. Even though the threaded portion of the rotary cutting body 1 is damaged, such as due to wear and tear, the cutting insert 3 can be kept in good condition so as to prolong the service life span of the cutting insert 3. However, during the cutting process, the cutting insert 3 will generate a cutting force F1 at the outer lateral side of the cutting insert 3. On the other hand, the supporting point O is formed at a connection between the clamp 2 and the outer lateral side of the rotary cutting body 1, wherein the supporting point O is a point to support the clamp 2 within the insert pocket 11, such that a distance between the cutting force F1 and the supporting point O is formed. As a result, the rotary cutting body 1 is easily distorted or cracked at the supporting point O. It is because a torque is generated in response to the cutting force F1 and the supporting point O, such that the clamp fastener 4 must provide enough clamping force F2 to against the torque. It is worth mentioning that the engagement between the rotary cutting body 1 and the clamp 2 is secured only by the clamp fastener 4. When the cutting force F1 increases, the clamping force provided by the clamp fastener 4 must be increased. Since the hardness and the stiffness of the rotary cutting body 1 are low, the distortion and crack will happen on the rotary cutting body 1. In addition, the clamp 2 and the cutting insert 3 will be easily loosen or displaced, such that the cutting precision of the cutting insert 3 will be reduced. In severe cases, the cutting insert 3 can be deformed or even broken due to the excessive force during the cutting process, which will cause serious problems.